Yerba Mate (Roasted) in Bulk?

Does anyone know of an affordable site or brand of roasted Yerba Mate?

Sites like yerbamate.us have green yerba mate in bulk (i.e. 1 kilo) for about $5, but they don't seem to have any roasted varieties/brands. Is roasted mate just unpopular in South America? I like the roasted mate from Specialteas, but I don't want to pay American prices (i.e. $20-25 per kilo).